Powered devices have been developed for digging and/or transplanting individual trees and the like, which would otherwise be a laborious and time-consuming task. Such devices are commonly referred to as "tree spades" and are available from the Vermeer Mfg. Co., of Pella, Iowa, and Big John Mfg. Co. of Little Rock, Arkansas. Tree spades generally include hydraulically actuated blades arranged in a generally conical pattern pivoted about a horizontal axis on the back of a trailer or truck. However, such tree spades are limited to transporting a single tree per trip and if multiple trips are required and/or some distance is involved, it will be appreciated that this can be both expensive and time-consuming.
Trailers for transporting multiple trees have been available heretofore. For example, U.S. Pat. No. 3,032,368 to Sigler shows a tree trailer having a plurality of freely pivotal receptacles arranged in a line, in stepwise fashion so that the trees will overlap each other for maximum overhead clearance when the receptacles are pivoted during transport. A boom is used to lift the trees onto or off of the trailer, which is not adapted for use with a hydraulic tree spade. U.S. Pat. No. 3,782,773 to Mason shows a reusable tree carrier wherein carrier devices in the form of right octagonal cones can be positioned in pivotal collars located in staggered arrangement on the trailer. Both of these trailers require some form of crane for lifting the trees or the trees and their carriers onto and off of the trailer.
Tree transport trailers which are adapted for use directly with hydraulic tree spades have also been available heretofore. For example, U.S. Pat. No. 4,351,253 to Dahlquist shows a trailer including pairs of cone shaped containers pivotal about transverse axes. U.S. Pat. No. 4,604,017 to Boehm illustrates another tree transporter wherein the containers are pivotal about diagonal, inclined axes so that the trees overlap when the containers are in the transport position, but pivot outwardly when in the loading/unloading position to facilitate cooperation with the tree spade. These trailers, however, require additional jacks and/or structural reinforcement to handle the extra loads imposed by the hydraulic tree spade. This in turn adds weight and cost, both in manufacturing and operating.
There is thus a need for a tree transport trailer of improved construction which is adapted for use directly with hydraulic tree spades, but which is designed to avoid any additional jacks or reinforcement in order to achieve cost savings, and which also is adapted for either individual or simultaneous actuation of the carriers between the loading/unloading position and the transport position.